To get the best workout, we turned to New York University physical-therapy professor Marilyn Moffat, who wrote the book " Age Defying Fitness."

Moffat walked us through the best exercises for your arms that require little to no equipment.

These workouts are even better in combination, so feel free to mix and match. Repeat or hold each exercise until it gets to be too much, building up at your own pace. And remember: If you encounter any unusual pain or problems as you work out, stop and consult a doctor or physical therapist.

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Exercise #1: Get started in a plank. A standard plank works more than just your arms, but it's key to activating everything from your forearms to your deltoids.

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For a modified plank, go onto your forearms. You'll still feel the burn along your arms. It might be worth using a yoga mat for this one.

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If you want to take your plank to the next level, lift up one leg for a few seconds. Then do the other one.

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My wrists always feel pressure from planks (which Moffat said is the correct response). To counteract the pressure, spread your fingers as wide as possible to distribute your weight.

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Exercise #2: Side planks. In addition to feeling this along your obliques, both arms should feel activated.

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Modification: To tone down the workout, place your forearm and top leg on the ground, while still reaching that top arm up (ideally straighter into the air).

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Exercise #3: Chair push up. Grab a chair — ideally near a wall for safety — and position yourself as though you're about to sit on the edge. Instead of taking a seat, put your arms on the chair and lower yourself down below its edge.

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While down, keep your elbows back and close to your sides, not splayed out to the left and right. Your back should be straight and close to the chair (and your neck should be in line with your body, not pulled forward like I have it here). Repeat these chair push-ups, increasing the amount you do every time.

Try to keep your neck in line with your body (mine is a bit too far out).
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For all of these, start with two repetitions to see how you feel, and then try to get up to eight or 12 repetitions before you get too tired.

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Modification #1: For a different feel, place your legs straight out in front of you, moving up and down.

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Pushing up is the hardest part. Remember to keep your arms close to your sides.

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Modification #2: If you really want to push your arms to the extreme, place one hand on the chair and hold the other out in front of you. Repeat with the other arm.

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Exercise #4: Reverse chair push up. Moffat said she prefers to use the chair to do a modified push up, since it's a way to get your body moving that's feasible for everyone. This can also be done with your legs straight rather than bent.

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Exercise #5: Toes on the chair. Placing your feet on the chair, lower yourself down through a push-up position. This push-up modification might be my favorite.

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Be careful not to over-extend your back on this one. Once you're lowered down, push back up to straight arms.

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Exercise #6: Reverse plank. Ditch the chair and go for a reverse plank on your forearms, putting your body in a full diagonal with your head back, in line with your body. You should really feel this one along your triceps.

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Exercise #7: Burpees. Add some motion with a modified set of burpees — no vertical jump required.

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Modification #1: Instead of jumping into the pose, bring each leg up toward your hands one by one. This should still give the arms a good workout.